Attachment G.pdf

720.1 720.4.1

SECTION 720

CONCRETE CURB, GUTTER, CURB AND GUTTER,

SIDEWALK, DRIVEWAY, AND MEDIAN

720.1 Description

This section contains specifications for the materials, construction, equip-ment, measurement, and payment for the construction of Portland cement concrete curb, Portland cement concrete gutter, Portland cement concrete curb and gutter, Portland cement concrete sidewalk, Portland cement con- crete driveway, and Portland cement concrete median in one course on a prepared subgrade in accordance with these specifications, conforming to the dimensions, typical cross-section, and notes shown on the Plans, and to the lines and grades shown on the Plans or established by the RCE.

2 This work includes the placing of reinforcing steel in the concrete when in-dicated on the Plans.

720.2 Materials

720.2.1 Portland Cement Concrete

Provide Class 2500 Portland cement concrete conforming to the applicable requirementsof Section 701.

720.2.2 Expansion Joint Material

Provide expansion joint materials meeting the requirements of Subsection 702.2.2.1.

720.2.3 Reinforcing Steel

Provide reinforcing steel conforming to the requirements of ASTM A 706, Grade 60, and meeting the applicable requirementsof Section 703.

720.3 Equipment

Ensure that the equipment necessary for/ the proper construction of the work is on site, in acceptable working condition, and approved by the RCE as to both type and condition before the start of work under this section. Provide sufficient equipment to enable prosecution of the work in accordance with the project schedule and completion of the work in the specified time.

720.4 Construction

720.4.1 Subgrade

Thoroughly compact the subgrade and finish to a smooth, firmly compacted surface, which is moist at the time the concrete is placed. In areas where it is impractical to use standard type rollers, accomplish compaction by vibratory hand compactors. Remove and replace concrete that settles and/or cracks after placement as directed by the RCE without additional compensation.

720.4.2 720.4.5

720.4.2 Forms

Use wood or metal forms of a depth equal to the thickness of the concrete course. Make certain they are free from warp and are of sufficient strength when staked, to hold the alignment during the concrete placing and finishing operations. Before concrete is placed against them, clean and oil the forms.

Use flexible or curved forms on curves as necessary in order to prevent a chord effect in the alignment of the finished work.

720.4.3 Existing Sidewalks and Driveways

Where a portion of an existing sidewalk or driveway is reconstructed, cut the existing section to a minimum depth of 2 inches with a suitable saw at the location designated by the RCE and remove the entire section to be recon-structed. Join the new sidewalk or driveway with the old work at this line.

720.4.4 Mixing and Placing Concrete

Batch and mix the concrete in accordance with the applicable requirements of Section 701.

2 Unl ess otherwise indicated on the Plans, construct concrete curbs, con-crete gutters, and concrete curb and gutters in uniform 10-foot sections, ex-cept where shorter sections are necessary for closures; but ensure that no section is less than 4 feet in length. Separate the sections by sheet steel templates or dividing plates set normal to the face and top of the curb. Care-fully set the plates during the placing of the concrete and keep in place until the concrete has set sufficientlyto hold its shape. Remove the plates while the forms are still in place.

3 Deposit concrete in the forms so that the forms do not displace out of grade or alignment. During the placing operations, spade or vibrate the concrete throughout the entire mass and especially against the forms and joints. Tamp, float, trowel, broom, edge, and finish the surface of the concrete to the typical section, lines, and grades as soon as practicable after the placing of the concrete. Leave the forms in place until the concrete has set sufficiently and their removal does not injure the concrete.

720.4.5 Extruded or Slip-Formed Curb or Curb and Gutter Construction

, Unle ss otherwise specified and except on structures, concrete curb may be placed by an extrusion machine acceptable to the RCE. An accepted slip-form machine may be used to construct concrete curb or curb and gutter if satisfactory results are obtained. When, in the opinion of the RCE, satisfac-tory results are not being obtained, discontinue the extrusion or slip-form work and use the stationary form type of construction with no adjustment in com-pensation. Remove and replace L;Jnsatisfactory work without any additional compensation.

2 Construct expansion and weakened joints at the same locations as re- quired when form construction is being used. Make weakened joints, spaced at 10 foot intervals, by cutting the plastic concrete with a trowel or by other

720.4.6 720.4.7.1 acceptable methods. Ensure that the manner of construction of joints meets the approval of the RCE and has a workmanlike finish after edging.

720.4.6 Joints

720.4.6.1 Expansion Joints

Ensure that preformed expansion joints are¾ inch thick and extend the full-depth of the concrete. Construct joints at the locations indicated on the Plans and at the following locations:

• Wherever a sidewalk is constructed between an adjoining substantial structure on one side and curbing on the other side, form an expan-sion joint adjacent to the curbing.

• Place an expansion joint between the sidewalk and the radius curb-ing at street intersections.

• Where concrete sidewalks or medians are constructed adjacent to existing or new concrete pavement or structures, place a transverse expansion joints in the sidewalk or median opposite such joints in the concrete pavement or structure.

• Where existing structures such as light standards, poles, fire hy-drants, etc., are within the limits of the sidewalk or median area, sur-round them with an expansion joint.

• Place transverse expansion joints at intervals of not more than 100 feet in all concrete shapes.

720.4.6.2 Contraction Joints

Divide the concrete slabs in sidewalks between expansion joints into blocks 10 feet in length, by scoring transversely after floating operations are com-pleted. Where the sidewalk slabs are more than 10 feet in width, score them longitudinally in the center. Extend transverse and longitudinal scoring for a depth of 1 inch and not less than ¼ inch or more than ½ inch in width. Edge and finish joints smooth and true to line.

2 In concrete medians, locate transverse contraction joints, formed as de-scribed above, at intervals of not more than 25 feet and extend not less than a quarter of the median depth.

720.4.7 Final Finish

720.4.7.1 Curbs and Curb and Gutters

As soon as the concrete has set sufficiently, remove the forms from the exposed surfaces. Float and trowel the concrete on the curb face and top as necessary to provide a smooth uniform finish. Leave joint templates in place a minimal length of time to prevent bonding or distortion at the joint.

2 After the surface of the gutter has been properly shaped and prepared and the water sheen has disappeared, produce the final finish by brooming. Apply brooming transverse to the line of traffic. Ensure that joints are in a vertical plane perpendicular to the curb face. Make certain that joints are clean and

720.4.7.2 720.5 corners well rounded. Edge corners and conform to the typical cross-section.

Eliminate all tool marks in final finish.

720.4.7.2 Sidewalks, Gutters, Medians, and Driveways

Apply the final finish for sidewalks, gutters, medians, and driveways by brooming as specified in Subsection 720.4.7.1, unless otherwise directed. As soon as the forms are removed from concrete median, rub down the sides to a smooth and uniform finish. Remove mortar or aggregate particles that spill onto the pavement.

720.4.7.3 Repair of Defects

As soon as the forms are removed from all concrete shapes, fill honey-combed places and other minor defects with a mortar composed of one part Portland cement and two parts sand. Plastering is not allowed. Replace sec-tions with visible cracks at no expense to the Department.

720.4.8 Protection and Curing

Protect the concrete as specified in Subsection 702.4.6 and cure with liq-uid membrane-formingcompounds meeting the requirements of Subsection

702.2.2.11. Ensure that methods and rates of application of curing com-pounds are in accordance with Subsection 702.4.4.2.

720.4.9 Backfilling

After the concrete has set sufficiently and the forms have been removed, backfill the spaces on both sides to the required elevation with suitable mate-rial that is firmly compacted and neatly graded. Backfill concrete gutter so that the earth materials are a minimum of 1 inch above the concrete. Main- tain an earth roll on each side as necessary to prevent undermining of curb and gutter.

720.5 Measurement

The quantity for the pay item Concrete Curb, Concrete Gutter, or Concrete Curb and Gutter (of the type and size specified) is the length of the cast-in- place curb and/or gutter and is measured by the linear foot (LF), complete, and accepted. Concrete Curb and Gutter is measured along the roadway face of the curb at the gutter line. Concrete Curb and Concrete Gutter are both measured along tlie roadway at the finished grade elevation.

2 The quantity for the pay items Concrete Sidewalk, Concrete Driveway, and Concrete Median is the finished surface area of the top of the cast-in-place sidewalk, driveway, or median and is measured by the square yard (SY), complete, and accepted. Deductions for drainage structures such as catch basins, drop inlets, etc., are in accordance with the Plans, the Specifications, and SCOOT Standard Drawings.

3 Excavation, when applicable and approved, is measured for in accordance with Subsection 203.5